How would you account for the fact that actinoids exhibit a larger number of oxidation state than the corresponding lanthanoids?

Answer

Actinoids show a larger number of oxidation state because the energy gap between `5f,6d` and `7s` subshells is very small and hence all the electrons present in these subshells can participate in bonding whereas lanthanoids show a limited number of oxidation state because the energy gap between `4f` and `5d` subshells is large and all the electrons in the these subshells cannot participate in bonding.